The graph-isomorphism conjecture for rational quadratic-form graphs

Let q1,q2q_1,q_2\boxtimes be quadratic forms on Qn\operatorname{\mathbb{Q}}^n, and let G0(Qn,q)G_0(\operatorname{\mathbb{Q}}^n,q) denote the connected component containing 0\operatorname{\textbf{0}} in G(Qn,q)G(\operatorname{\mathbb{Q}}^n,q). Write q1Qq2q_1\stackrel{\operatorname{\mathbb{Q}}}{\sim}q_2 when the forms are rationally equivalent. Graph-isomorphism conjecture. If G0(Qn,q1)G0(Qn,q2)G_0(\operatorname{\mathbb{Q}}^n,q_1)\simeq G_0(\operatorname{\mathbb{Q}}^n,q_2), then q1Qq2q_1\stackrel{\operatorname{\mathbb{Q}}}{\sim}q_2. Moreover, every isomorphism between these graphs is a linear transformation TT such that

q1(x)=q2(Tx).q_1(\operatorname{\textbf{x}})=q_2(T\operatorname{\textbf{x}}).

This conjecture generalises the rational Beckman--Quarles theorem: when q1=q2=Inq_1=q_2=I_n, it asserts that every automorphism of G0(Qn,In)G_0(\operatorname{\mathbb{Q}}^n,I_n) is an isometry.

Sources & referencesView supporting material

Primary source

Artemy Sokolov, “On distance graphs in rational spaces”, arXiv:2301.06954 (2023).

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